Detecting key actuation in a keyboard

ABSTRACT

A system and method for detecting key actuation in a keyboard assembly, which, in one embodiment, is used as a conductor to electrically communicate with an information appliance. The rows in the keyboard assembly are electrically isolated from one another, and each row contains keys bridging a two-wire bus. Each key has a switch that is closed during key actuation, a diode to polarize the key, and a resistor to provide a resistive load when the switch is closed and the diode is biased with the current flow. Alternatively, each key has a switch that is closed during key actuation, a timer with an output that goes high after a predetermined time period, and a resistor that provides an identifying load when the switch is closed and the output of the timer is high. Other features of the invention include a linear matrix coupled to a row of keys to allow the row to be scanned by sections and individual keys, and a flexible circuit that provides the electrical pathways for the linear matrix.

PRIORITY CLAIM

This application is a Continuation of U.S. Ser. No. 10/367,140, filedFeb. 14, 2003 (now issued U.S. Pat. No. 7,084,787, issued Aug. 1, 2006)entitled SYSTEM AND METHOD FOR DETECTING KEY ACTUATION IN A KEYBOARD;which is a Divisional of U.S. Ser. No. 09/191,067, filed Nov. 12, 1998(now issued U.S. Pat. No. 6,563,434, issued May 13, 2003) entitledSYSTEM AND METHOD FOR DETECTING KEY ACTUATION IN A KEYBOARD, and claimspriority of U.S. Provisional Ser. No. 60/065,181 filed Nov. 12, 1997entitled COLLAPSIBLE KEYBOARD ASSEMBLY.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to systems and methods for detecting keyactuation in keyboard assemblies for information devices, and moreparticularly to systems and methods for detecting key actuation inkeyboards for such devices.

2. Background Information

Small portable computers or “palmtops” can be conveniently carried in apurse or coat pocket. Recent advances in shrinking the size ofelectronic components will soon allow these devices to perform all thefunctions of today's desktop computers. Additionally, a whole newcategory of “information appliances” has begun. These include portablewireless telephone/computers which can be used to access the Internet tosend and receive e-mail and to interact on the World Wide Web.

Powerful and versatile as these devices are becoming, their use isgreatly limited by non-existent or inadequate keyboards. Palmtops whichrely on handwriting recognition have proven to be awkward, slow anderror prone. Miniature keyboards commensurate with the size of smallappliances are likewise frustrating, especially if the user needs towrite something consisting of a few sentences or more. Voice recognitionsuffers from frequent errors and creates a lack of privacy when otherpeople are near the speaker whose voice is being recognized. Further,voice recognition may not be used in all circumstances (e.g. the processof taking notes of a lecturer's lecture in an otherwise quiet auditoriummay not be possible with voice recognition input systems but it isusually possible with a keyboard).

Keyboards for desktop and high quality laptop computers allow the userto comfortably, privately, quietly, and quickly “touch-type.” They havea number of desirable features in common. Most keyboards have a standard“QWERTY” layout which requires no learning on the part of the user (oncethe user has become familiar with this layout). The keys, which usuallynumber 84 for a laptop computer, have full-sized tops whosecenter-to-center spacing is about 19 mm for both the horizontal andvertical axes. The length of the keyboard (the distance from the leftedge of the left-most key to the right edge of the right-most key) isabout 11 inches. Any reduction in this spacing has proven to slow downand frustrate the touch-typist. Additionally, the keys of thesekeyboards have sufficient “travel,” the distance the key moves when itis pressed, and tactile feedback, an over-center buckling action, thatsignals the user that the key has been pressed sufficiently.

Efforts have been made to provide keyboards that contain these features,yet collapse to a reduced size. Some designs only slightly reduce thesize of “notebook” computers when folded. These are much larger thanpalmtop computers. IBM's “ThinkPad 701C” notebook computer folds in asingle operation to reduce the keyboard case length (measured from theedges of its case) from 11.5 inches to 9.7 inches. Also see U.S. Pat.No. 5,543,787 which describes a foldable keyboard. U.S. Pat. No.5,519,569 describes a keyboard which folds in multiple steps from alength of 10-11 inches to 6.125 inches. U.S. Pat. No. 5,654,872describes a keyboard with keys that collapse when the lid is closed toallow a thinner notebook computer.

Other designs of keyboards include those where the keyboard is hinged atthe center of its length and folds about a vertical axis. U.S. Pat. No.5,457,453 describes a keyboard that folds to greater than half itslength. U.S. Pat. No. 5,574,481 describes a keyboard that folds in halfand appears to have a non-standard layout of keys (the keys on thecenter fold axis have edges which lie in a straight line). U.S. Pat. No.5,653,543 describes a keyboard that folds in half. U.S. Pat. No.5,502,460 describes a keyboard with two vertical hinges that folds togreater than half its unfolded length.

U.S. Pat. Nos. 5,044,798 and 5,141,343 describe keyboards whose keyshave user-selectable variable spacing. These designs have non-standardlayouts (e.g., the “Enter” key is rotated ninety degrees) and noself-containing housing. Their frame is made of telescoping sectionsthat create a good deal of friction and could easily bind.

Keyboards electrically communicate information to informationappliances. Most keyboards have printed circuit boards or membraneslocated underneath their keys. When a key is pressed it shorts thecircuits in a particular column or row. The matrix of columns and rowsthat make up a keyboard is continually scanned by a controller todetermine which keys have been pressed. Such an arrangement isdescribed, for example, in U.S. Pat. No. 5,070,330. The electronicconfiguration of most keyboards thus necessitates a matrix of conductorsthat limits the collapsing of the keyboard to a certain size.

SUMMARY OF THE INVENTION

The present invention provides, in one example of the invention, asystem and method for detecting key actuation in a keyboard assembly. Inone embodiment, the keyboard assembly is a collapsible keyboard whichincludes a support element and a plurality of keys. The support elementcan be extended to provide a structure having a first footprint andcontracted to a structure having a second footprint, where the secondfootprint takes less surface area than the first footprint. Theplurality of keys are coupled to the support element. Each of these keysincludes a key top, which is designed to be pressed by a user, and a keybase which is coupled to the key top. The key top and the key baserotate, in one example of the invention, on a pivot point which couplesthe key base to the support element when the support element is extendedand contracted.

In one exemplary embodiment, the invention provides detection of keyactuation for a keyboard assembly that is capable of collapsing into itsown protective housing. The housing consists of two symmetrical hollowbox-shaped members, opened on one side. When closed, it forms adust-proof enclosure surrounding a keyboard mechanism. When the keyboardassembly is in its collapsed position or state, it measures about4.0-4.7 inches vertically (depending on the inclusion and height of“function” keys), 3.25 inches horizontally, and 1.25 inches deep. In thecollapsed state, the keyboard assembly can be carried in a purse or coatpocket along with a palmtop computer or other information appliance,such as a cellular phone. Its small size allows it to be convenientlystowed inside an appliance, such as a desktop telephone or television.When used with desktop computers or other information appliances, thecollapsed state may be used to better utilize desk space when thecomputer is not in operation.

Expanding the keyboard from a collapsed state to a keyboard havingconventionally spaced keys is done in a single step in one example ofthe invention. The user simply pulls the two halves of the protectivehousing apart. The housing remains attached, so it cannot be misplaced,and so the unit can be enclosed and protected in an instant. The housingmay also include a cursor control device or a pointing device such as atouch-sensitive trackpad or joystick-like device such as IBM'sTrackPoint (found on IBM's ThinkPad laptop computers). This cursorcontrol device is, in one exemplary embodiment, selectively positionableon either the left or the right sides of the keyboard.

In one embodiment of the invention, key actuation detection is providedfor a keyboard assembly having keys coupled to and supported by asupport element which is a series of rows of multiple scissors-like,diagonally or X-shaped hinged linkages connected to the assemblyhousing. The linkages are selectively shaped such that any keyboardlayout may be adopted, including the standard ‘QWERTY’ layout with itsstaggered columns and various width keys. The linkages also provide awide ratio of contraction, yet due to their diagonal shape whenexpanded, provide a strong and rigid structure. The hinged linkagescreate very little friction and do not require lubrication, so thekeyboard assembly can be repeatedly opened and closed smoothly andeasily. The keys are pivotally attached to the linkages, and by means ofswing arms, pivot from a near vertical position, when the keyboardassembly is collapsed, to a horizontal position, when the keyboardassembly is expanded. To provide for a more compact profile when theassembly is collapsed, the keys are compressed to a closed and nestingposition.

In one exemplary embodiment of the invention, the mechanical structureof the keyboard assembly is used as a conductor to electricallycommunicate with an information appliance. The rows are electricallyinsulated from one another, and each row contains keys bridging atwo-wire bus. The rows are sequentially scanned by a controller. Inanother embodiment, each key has its own transponder circuit whichidentifies the particular key. When a key is pressed and the controllerscans the row the key is in, the key's transponder circuit indicates theidentity of the key.

In another embodiment of the invention, the keys in each row of akeyboard assembly are arranged in two polarity groups by a diode coupledto each key. Each key in a polarity group has a different resistive loadprovided by a coupled resistor. Polarizing the keys allows the highestand lowest resistor values to define a reasonable range. Each keyincludes a key switch which is normally open and is closed when the keyis pressed. When the switch is closed and the diode is biased with thecurrent flow, the resistor will determine the resistive load of thepressed key. The keys in each row are coupled in parallel between twoconductors.

In another embodiment of the invention, a keyboard assembly has rows ofkeys in which the keys in each row bridge two buses. Each key has atimer coupled to a switch and an electrical identifier, such as aresistor. The output of each timer goes high after a particular timeperiod. When the switch is closed and the output of the correspondingtimer is high, the electrical identifier provides an identifying load. Asignal is sampled at different times to determine if the signal ischanged by the identifying load. If so, a pressed key will beidentified.

In yet another embodiment of the invention, a linear electrical matrixis coupled to a row of keys. The row is electrically separated intosections, each of which has its own section pathway for signals. Eachkey in each section is coupled to a key pathway, which is shared bycorresponding keys in each section. Each row has its own set of sectionand key pathways, making the row appear electrically as if it werearranged in a matrix and allowing the rows to be electrically isolatedfrom one another. In one embodiment, all sections are scannedconcurrently to detect any responses from the keys. If a response signalis detected, the sections are scanned individually to identify the keythat provided the response signal.

In still another embodiment of the invention, a two layer flexiblecircuit passes through each key assembly in a row of keys and providesthe electrical pathways for a linear electrical matrix. The flexiblecircuit has an upper layer with a contact region disposed over thecontact region of a lower layer. Conductive traces on each layer act assection and key pathways to allow signals to travel along the row of thekeys. The flexible circuit is guided down between keys of a keyboardassembly, allowing the keyboard assembly to be collapsed more easily.

In one example of a method according to the invention, a row of keys iselectrically separated into different sections. The different sectionsare then scanned sequentially to detect a key actuation signal thatcorresponds to a pressed key. A scan code corresponding to the keyactuation signal is sent to a host computer.

Additional features and benefits of the invention will become apparentfrom the detailed description, figures, and claims set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not by way oflimitation in the figures of the following drawings in which likereference numerals refer to similar elements.

FIG. 1 is a planar top view of an embodiment of the keyboard assembly inits expanded position or state in accordance with the invention.

FIG. 2 is a planar top view of an embodiment of the keyboard assembly inits collapsed position or state in accordance with the invention.

FIG. 3 is a planar front view of an embodiment of the keyboard assemblyin its fully expanded position in accordance with the invention.

FIG. 4 is a planar front view of an embodiment of the keyboard assemblyin a semi-collapsed position in accordance with the invention.

FIG. 5 is a planar front view of an embodiment of the keyboard assemblyin its fully collapsed position in accordance with the invention.

FIG. 6 is a planar front view of three keys in Row I of an embodiment ofthe keyboard assembly in their expanded position in accordance with theinvention.

FIG. 7 is a planar front view of the three keys illustrated in FIG. 6 ina semi-collapsed position.

FIG. 8 is a planar front view of three keys illustrated in FIG. 6 intheir fully collapsed position.

FIG. 9 is a planar rear view of three keys in one row illustrated inFIG. 6 in their fully collapsed position.

FIG. 10 is a planar top view of seven keys in two rows of an embodimentof the keyboard assembly in accordance with the invention.

FIG. 11 is an embodiment of a key mechanism for a key in its openposition in accordance with the invention.

FIG. 12 is an embodiment of the key mechanism of the key in FIG. 11 inits closed position in accordance with the invention.

FIG. 13 is a top perspective view of ten keys in three rows of anembodiment of the keyboard assembly in their expanded position inaccordance with the invention.

FIG. 14 is a planar front view of three keys in Row III of an embodimentof a keyboard assembly in their fully expanded position in accordancewith the invention.

FIG. 15 is a planar front view of the three keys in Row III of FIG. 14in a semi-collapsed position.

FIG. 16 is a planar front view of the three keys in Row III of FIG. 14in their fully collapsed position.

FIG. 17 is a planar front view of three keys in Row V of an embodimentof a keyboard assembly in their expanded position in accordance with theinvention.

FIG. 18 is a planar front view of the three keys in Row V of FIG. 17 intheir collapsed position.

FIG. 19 is a planar rear view of the three keys of FIG. 17 in theircollapsed position.

FIG. 20 is a planar rear view of an embodiment of the inventionincluding tilt fingers with three keys in their fully expanded positionin accordance with the invention.

FIG. 21 is a planar side view of an embodiment of the keyboard assemblyof the invention in its expanded position having tilt fingers raisingthe back side of the assembly in accordance with the invention.

FIG. 22 is a planar rear view of the three keys of FIG. 20 in asemi-collapsed position.

FIG. 23 is a planar rear view of the three keys of FIG. 20 in theirfully collapsed position.

FIG. 24A is a top perspective view of a portion of an embodiment of akeyboard assembly in an expanded or open position in accordance with theinvention.

FIG. 24B is a top perspective view of the keyboard portion shown in FIG.24A in a collapsed or closed position in accordance with the invention.

FIGS. 25A and 25B are two perspective views of a male strut used in akeyboard assembly in accordance with the invention.

FIGS. 26A and 26B are two perspective views of a female strut used in akeyboard assembly in accordance with the invention.

FIGS. 27A and 27B are two perspective views of an actuator used in akeyboard assembly in accordance with the invention.

FIGS. 28A and 28B are two perspective views of a key base used in akeyboard assembly in accordance with the invention.

FIGS. 29A and 29B are two perspective views of another key base used ina keyboard assembly in accordance with the invention.

FIG. 30A is a planar front view of a portion of an embodiment of akeyboard assembly in an expanded position in accordance with theinvention.

FIG. 30B is a planar front view of the keyboard portion shown in FIG.30A in a partially collapsed position in accordance with the invention.

FIG. 30C is a planar front view of the keyboard portion shown in FIG.30A in a fully collapsed position in accordance with the invention.

FIGS. 31A and 31B are two perspective views of a key clip used in akeyboard assembly in accordance with the invention.

FIG. 32 is a flowchart of a method performed in accordance with theinvention.

FIG. 33 is a flowchart of another method performed in accordance withthe invention.

FIG. 34 is a flowchart of yet another method performed in accordancewith the invention.

FIG. 35 is a top view of an embodiment of the electrical layout of fourkeys of the keyboard assembly in accordance with the invention.

FIG. 36 is a schematic circuit diagram of an embodiment of a key encoderfor a key assembly for a keyboard assembly in accordance with theinvention.

FIG. 37 is a schematic electrical block diagram of a typical row of keysof a keyboard assembly in accordance with an embodiment of theinvention.

FIG. 38 is a schematic electrical block diagram of a partial row of keysof a keyboard assembly in accordance with the invention.

FIG. 39 is a schematic block diagram of a keyboard array coupled to ahost computer through a keyboard interface and a microcontroller inaccordance with an embodiment of the invention.

FIG. 40 is a schematic circuit diagram of a keyboard interfacecontroller circuit in accordance with an embodiment of the invention.

FIG. 41 is a schematic block diagram of three rows of keys coupled to ahost computer in accordance with an embodiment of the invention.

FIG. 42A is a schematic circuit diagram of an embodiment of a keycircuit for a key assembly used in a keyboard assembly in accordancewith the invention.

FIG. 42B is a schematic electrical block diagram of a partial row ofkeys of a keyboard assembly in accordance with the invention.

FIG. 43 is a schematic circuit diagram of a keyboard interfacecontroller circuit used with a keyboard assembly in accordance with theinvention.

FIG. 44 is a schematic block diagram of a keyboard array coupled to ahost computer through a keyboard interface and a microcontroller inaccordance with the invention.

FIG. 45 is a timing diagram of key signals from a keyboard assembly inaccordance with the invention.

FIG. 46 is a schematic circuit diagram of a linear electrical matrixcoupled to a row of keys of a keyboard assembly in accordance with theinvention.

FIG. 47 is a schematic block diagram of a keyboard array coupled to ahost computer through a keyboard interface and a microcontroller inaccordance with the invention.

FIG. 48A is a planar top view of a flex circuit layer used in a keyboardassembly in accordance with the invention.

FIG. 48B is a planar top view of another flex circuit layer used in akeyboard assembly in accordance with the invention.

FIG. 48C is a planar top view of a flex circuit with two layers used ina keyboard assembly in accordance with the invention.

FIG. 48D is an example of another embodiment of an array of keys inaccordance with the invention.

FIG. 48E is an example of a keyboard array which includes a cursorcontrol device (e.g. a trackpad) that is selectively positionable oneither side of the keyboard.

FIG. 49 is a flowchart of a method performed in accordance with theinvention.

FIG. 50 is a flowchart of another method performed in accordance withthe invention.

FIG. 51 is a flowchart of yet another method performed in accordancewith the invention.

FIG. 52 is a flowchart of still another method performed in accordancewith the invention.

FIG. 53 is a diagram of a digital processing system, such as a personaldigital assistant which is substantially contained in a collapsiblekeyboard assembly according to one embodiment of the invention.

DETAILED DESCRIPTION

The invention relates to detecting key actuation in a keyboard assembly.Specific details of an embodiment of the keyboard assembly are describedbelow. Numerous specific details including keyboard layouts, specificstructural arrangements and relationships, etc. are presented in orderto provide a thorough understanding of the invention. It is to beappreciated that these specific details need not be specificallyemployed to practice the invention and that there are other details thatare not presented so as not to unnecessarily obscure the description ofthe invention that may be substituted or included that fall within thescope of the claimed invention.

FIG. 1 shows a planar top view of an embodiment of the keyboard assemblyof the invention. For convention, the rows of keys are numbered Ithrough VI, with Row I being closest to the user or the front of thekeyboard assembly. Row I includes the “Ctrl” key and row VI includes the“Pause” key. The “front” side of a key is closest to a user situatedclosest to Row I, while the “back” side of the key is farthest from theuser. A vertical distance is measured from the front of the keyboardassembly, closest to the user, to the back of the keyboard assembly,farthest from the user. A horizontal distance is measured from the left(or one side) of the keyboard assembly to the right (or other side) ofthe assembly.

FIG. 2 shows a planar top view of keyboard assembly 10 of FIG. 1 in itscollapsed state. For illustration purposes, in FIG. 2, the top portionof each of protective housing sides 1 and 2 is transparent so as toreveal the collapsed state of keys 3. FIGS. 3-5 illustrate a planarfront view of an embodiment of keyboard assembly 10 and show thecollapsible nature of keyboard assembly 10.

FIGS. 1 and 3 show a top and a front view, respectively, of anembodiment of keyboard assembly 10 in its expanded position. In FIG. 1,it can be seen that the layout of keys 3 of the keyboard assembly 10 isthe same as the standard keyboard. In this embodiment, spacing betweenkeys 3 is full pitch (about 19 mm) in both horizontal and verticaldirections. It is to be appreciated that the invention is not limited tothe keyboard layout presented and that other layouts may be substitutedwithout departing from the scope of the invention. For example, thekeyboard may be a numeric keypad or a set of keys providingpreprogrammed functions. As can be seen from FIG. 3, a row ofinterconnected scissors linkages 4 is coupled at each of both ends ofthe row to a housing. The row of linkages 4 supports a row of keys. Eachkey includes a key top 11 a and a key base 11 b. For each key, the keytop 11 a is coupled to the corresponding key base 11 b. Typically, thecoupling is by some mechanism which imparts a spring action to the keytop relative to the key base such that the key top resists being pressedtoward the key base when the key top is pressed during typing. Pressingthe key top toward the key base usually causes an electrical connectionto be changed; usually this occurs by a switch on the key base beingclosed when the key top is pressed far enough toward the key base,although other implementations may not require a switch.

As shown in FIG. 3, the row of scissors linkages 4 includes a pluralityof scissors linkages which are connected in series. Three such scissorslinkages 4 a, 4 b, and 4 c are shown in FIG. 3 and are connected fromleft to right respectively. Each scissors linkage includes two legswhich are coupled together at a pivot point by a pin or rivet. Eachscissors linkage is coupled to the next scissors linkage in the row by apivot point on one leg and a pivot point on another leg. Further detailsregarding the scissors linkages of one embodiment of the invention aredescribed below.

When not in use, keyboard assembly 10 may be kept in its collapsedposition or state by a protective housing composed of sides 1 and 2.FIGS. 2 and 5 illustrate planar top and front views, respectively, ofkeyboard assembly 10 in its collapsed position with protective housingsides 1 and 2 covering collapsed keys 3. To open the keyboard foroperation, the user holds left and right sides 1 and 2, respectively,and pulls linearly sides 1 and 2 apart. FIG. 4 shows a front view ofkeyboard assembly 10 in a partially expanded or semi-collapsed positionor state. The user continues to pull apart sides 1 and 2 until thekeyboard assembly stops expanding (FIGS. 1 and 3).

The keyboard assembly stops expanding, in one embodiment, when the twoend legs on each side of a row of scissors linkages are restricted fromclosing down upon each other. This can be seen from FIG. 3 which showsthat a row of scissors linkages 4 is coupled on each side of the row toa pivot point within the respective housing. Specifically, the housing 2on the right side of the keyboard assembly is coupled to the row ofscissors linkage at pivot points 24 and 23. This pivot point 23 includesan opening in a leg of the last scissors linkage on the right side ofthe row, and a pin or rivet which extends through the opening and whichis attached to the inner wall of the housing 2. Pivot point 24 includesan opening in the other leg of the last scissors linkage on the rightside of the row and a pin or rivet which extends through the opening andwhich pin or rivet also rides in a channel 25 formed in the inner wallof the housing 2. The channel 25 allows the pin at pivot point 24 toride up and down the channel as the keyboard assembly is collapsed andextended respectively. Note from FIG. 4 how the pivot point 24 has movedto half-way along the channel 25 when the keyboard is semi-collapsed.The bottom end of the channel 25 defines the stopping point for theextension of the keyboard assembly. A similar arrangement exists at thelast scissors linkage on the left side of this row of scissors linkagesas shown in FIGS. 3, 4 and 5. A keyboard on/off switch at the end of thechannel 25 may be activated by a pivot point 24 when that pivot pointreaches the end of the channel at the end of the keyboard's expansion.In this way, the end of the keyboard's expansion may be automaticallysensed and power to the keyboard may be automatically supplied at thispoint. Each row of scissors linkages is typically coupled in a similarfashion to the inside of housings 1 and 2.

In one embodiment, the full extension of sides 1 and 2 turns on thekeyboard's power, via a limit switch, for example. In anotherembodiment, the full extension of sides 1 and 2 tilts the keyboard byraising the rear side. Once fully expanded, the assembly 10 cancommunicate directly with a computer or other host device via anelectric or electronic link. Examples of contemplated linkages include,but are not limited to, an infrared or radio frequency link, or a cable.

When not in operation, keyboard assembly 10 may be placed in itscollapsed position (FIGS. 2 and 5) by pushing protective housing sides 1and 2 together until the sides cover keys 3. A latch may determine theend point and the side portions may lock, for example, via a key lockswitch, to provide a measure of security. To provide the most compactfolded size while allowing one-step expanding and collapsing, in oneembodiment, keys 3 are pivotally linked to each other by a row ofscissors-like X-shaped linkages 4. FIGS. 3-5 show the collapsible andexpandable nature of linkages 4.

FIG. 6 shows a magnified view of three keys 3 of keyboard assembly 10coupled to a row of scissors or X-shaped units or linkages 4. As shownin FIG. 6, each scissors linkage is composed of two legs pivotallyjoined at hub 5, for example, by flanged pins or rivets 30. Eachscissors or X-shaped linkage is pivotally joined to a horizontallyadjacent scissors linkage at lower and upper hubs 6 and 7, respectively.

As shown in FIG. 6, three scissors linkages 4 a, 4 b, and 4 c areinterconnected in series along a row. Three keys are supported by thisrow. Each key 3 is supported by and coupled to two adjoining scissorslinkages. Scissors linkage 4 a is comprised of legs 4 d and 4 e whichare pivotally coupled at hub 5 (which is also referred to as a scissorspivot point) formed by overlapping openings in legs 4 d and 4 e. Thescissors linkage 4 a also includes an arm 8 which is rotationallycoupled to hub 6 (which is also referred to as a coupling pivot point)at one end of arm 8 and is rotationally coupled to hub 9 on the key base11 b of the left-most key of FIG. 6. Hub 6 is formed by overlappingopenings in arm 8, leg 4 e and leg 4 f. Hub 9 is formed by overlappingopenings in arm 8 and key base 11 b. Each of these hubs is secured by apin in one embodiment. Leg 4 d of scissors linkage 4 a is rotationallycoupled to leg 4 g at coupling pivot point 7; coupling pivot point 7 isalso rotationally coupled to the key base 11 b of this left-most key.Coupling pivot point 7 is formed by overlapping openings in leg 4 d, leg4 g and key base 11. Coupling pivot point 7 is secured by a pin in oneembodiment of the invention. Leg 4 e of scissors linkage 4 a isrotationally coupled to leg 4 f at the coupling pivot point 6. Legs 4 fand 4 g form the scissors linkage 4 b and are also rotationally coupledtogether by a scissors pivot point 5. Scissors linkage 4 b includes anarm 8 which is rotationally coupled at coupling pivot point 6 to leg 4 gand to leg 4 h of scissors linkage 4 c. The arm 8 of scissors linkage 4b is rotationally coupled to a key base 11 b of the middle key of FIG.6, and this key base is rotationally coupled to leg 4 f of scissorslinkage 4 b and to leg 4 i of scissors linkage 4 c. The leg 4 h and theleg 4 i form scissors linkage 4 c which is rotationally coupled to thekey base 11 b of the right-most key of FIG. 6. The legs 4 h and 4 i arepivotally coupled at the scissors pivot point 5. The key base 11 b ofthis right-most key is coupled to an arm 8 which extends from a couplingpivot point with leg 4 i and is coupled to leg 4 h at a coupling pivotpoint on this key base 11 b.

FIGS. 7-9 illustrate the pivoting of a row of linkages 4 with respect tothe three keys 3 of FIG. 6. Keys 3 rotate from a horizontal position(FIG. 6) when keyboard assembly 10 is fully expanded, to approximately a45° angle when keyboard assembly 10 is partially collapsed (FIG. 7), toa nearly vertical position (FIGS. 8-9) when keyboard assembly 10 isfully collapsed. FIG. 9 is a rear view of the collapsed portion ofkeyboard assembly 10 of FIG. 8. Arms 8 pivotally connect linkage hubs 6to hubs 9 of keys 3. When expanded, arms 8 and the row of scissorslinkages 4 provide a strong, rigid truss, and the angles assumed by arms8 and the row of scissors linkages 4 are such that keys are preventedfrom rotating even if they are pressed hard by the user.

As keyboard assembly 10 is collapsed (FIG. 7), hubs 6 and 7,respectively, increase in distance from each other. This causes arm 8 torotate key 3 via hub 9 from its horizontal position toward a verticalposition (in this case in a counterclockwise direction). Effectively,arm 8 pulls down the key 3 in a counterclockwise direction. Whenkeyboard assembly 10 is fully collapsed (FIGS. 8-9), the row of linkages4, arms 8, and keys 3 are, respectively, substantially parallel and, inone embodiment, in contact with one another. While FIG. 9 shows thatthere is some space between a key top of one key and a key base on theadjacent key, there may in certain embodiments be little or no spacebetween a key top on one key and a key base on an adjacent key.

In the embodiment described, bottom hubs 6, which pivotally join theX-linkages 4 and arms 8 at their base, are approximately horizontallyequally spaced. When keyboard assembly 10 is fully collapsed, hubs 6 arein close horizontal proximity to one another. This can be seen from FIG.5.

In one embodiment, each row of keys 3 of keyboard assembly 10 ispivotally joined to its adjacent row to provide a strong and stablestructure when keyboard assembly 10 is in an expanded position. FIG. 10shows a planar top view of a portion of keyboard assembly 10. FIG. 10shows a portion of keys 3 from Row IV pivotally coupled to keys 3 of RowV. Three rows of scissors linkages 4 hold these seven keys. Flanged pins29 extend through linkage hubs 7 on each row of scissors linkages andfasten to keys 3 to pivotally secure the top portion of keyboardassembly 10. Each of these pins 29 also pivotally secure at a hub 7 oneleg from one scissors linkage to a leg from an adjacent scissors linkageas shown in FIG. 6. Each row of scissors linkages 4 of FIG. 10 fastens,through these pins 29, to one side of each key along a row of keysthrough the corresponding hub 7. The other side of each key along thisrow is secured to an adjacent row of scissors linkages 4 through themating of another set of pins 29 in the corresponding hubs 7 on thisother side of each key. Flanged rods 31 (shown in FIG. 13) pass throughbottom hubs 6 on each of the three rows of scissors linkages and spacingsleeves 32 to pivotally secure the bottom portion of keyboard assembly10. Each pivot point at the connection between an arm 8 and a key base11 b at a hub 9 is secured by a flanged pin 9 a which extends throughthe opening in the arm 8 and into an opening in the key base 11 b. Asnoted above, flanged pins or rivets 30 are used to secure each scissorspivot point 5.

FIGS. 11 and 12 show a planar front view of an embodiment of a key 3 ofkeyboard assembly 10. In FIGS. 11 and 12, key 3 is composed of key base11 b that is coupled to key top 11 a by a conventional linkage havingbutterfly elements 12 and 48. This linkage allows key 3 to be compressedto a very thin dimension (FIG. 12), yet have a large amount of travel(the distance between its open and closed position). When keyboardassembly 10 is fully collapsed, adjacent keys 3 exert pressure on eachother causing them to be maintained in their closed position. It will beappreciated that there are numerous alternative types of linkages whichmay be used to link between each key top and key base.

Coupled to the base of key top 11 a of each key 3 is a spring 49 thathas the shape of a bowl or truncated cone and is made, for example, ofan elastomer or elastomer-like material. To type, a user presses on thekey top and compresses the spring 49 as the key top is pushed toward thekey base 11 b. When the compression of spring 49 exceeds a predeterminedamount, spring 49 buckles to give tactile feedback to the user. FIG. 12shows one example of the buckling of spring 49. The elastomeric natureof spring 49 also allows it to remain in a compressed position (whenkeyboard assembly 10 is collapsed) without fatigue.

FIGS. 11 and 12 show an example of a key assembly with a flexibleconductor assembly disposed on a key base. In this particular example, aflexible conductor assembly for each row of keys is weaved through keybases of the keys along the row; FIGS. 30A-30C show how this flexibleconductor assembly allows the key assemblies to rotate between anexpanded and a contracted state. A flexible conductor assembly willtypically include a plurality of flexible conductors disposed on or in aflexible film. The flexible conductor assembly may include one or two orthree or more layers of flexible conductors. The flexible conductorassembly bends as the keys of a row are collapsed and bends as the keysare expanded. Each row of keys has its own flexible conductor assemblywhich in one case is a set of 8 conductors in two layers of conductorsrunning along each row. One layer of conductors may represent “columnlines” and another layer of conductors may represent “row lines.” FIG.46 shows an example of “row lines” 801-804, each of which defines aseparate section of a mechanical row of keys and column lines 805-808,each of which is a “column” conductor that is coupled to a particularkey switch. The rows are electrically insulated from each other. FIGS.11 and 12 show an example of a three-layer flexible conductor assemblyin which the row conductor 801 is disposed above (and separated from) acolumn conductor 805 when the key top 11 a is not pressed down againstkey base 11 b. This three-layer flexible conductor assembly includes twolayers of conductive material and one layer of insulating material. Whenthe key top 11 a is pressed down against key base 11 b, the standoff 45a depresses the flexible film 45 b and the row conductor 801 toward thecolumn conductor 805, which causes the column conductor 805 on theflexible film 45 c to electrically contact the row conductor 801 asshown in FIG. 12, thereby closing the switch at this key between thesetwo conductors. It is assumed that in this case the electrical matrix ofFIG. 46 is being used with the embodiment of FIGS. 11 and 12. Theflexible films 45 b and 45 c are separated from each other by aninsulating layer 45 d which includes an opening allowing exposedconductive regions of row conductor 801 and column conductor 805 to makeelectrical contact. While FIGS. 11 and 12 show 2 layers of conductors inthe flexible conductor assembly, it will be appreciated that alternativeembodiments may use any number of layers of conductors. FIGS. 11 and 12show that the key top 11 a and key base 11 b are formed from differentstructures which are joined together. It will be appreciated that, in analternative embodiment, the key base and key top may be made from acollapsible unitary structure.

As can be seen in FIG. 1, the standard key layout of computer keyboardshas columns of keys which are mostly staggered, rather than in straightcolumns. Additionally, some keys, for example, the “Backspace” and“Enter” keys (FIGS. 1C and 5) are considerably wider than, for example,a letter key.

In order to allow the keyboard assembly of the invention to be collapsedto a minimum length and thickness, the particular embodiment depicted inthe figures utilizes various configurations of linkage shapes, armlengths, and hub locations on the keys. Additionally, the assembly isconfigured so that keys rotate in different directions in differentrows. FIG. 13 illustrates a perspective top view of a portion ofkeyboard assembly 10 of the invention. Note that there are threedifferent key top sizes. FIG. 13 shows a portion of three rows of keys 3(Rows III, IV, and V) and illustrates the support mechanism of such keysin part by ghost lines to indicate the construction of the mechanismbeneath the keys. Keys 3 are shown in an expanded (opened) position. InFIG. 13, hubs 6 lie in vertical columns and are equally spaced in allrows. Keys 3 in Row III are pivotally supported by the configuration ofa series of X-linkages 4, arms 8, and key hub locations shown in detailin FIGS. 14 and 15. As Row III collapses, keys 3 rotate in a clockwisedirection. The keys in Row IV are pivotally supported by theconfiguration shown in FIGS. 6-9. As Row IV collapses, keys 3 in row IVrotate in a counter-clockwise direction. This allows, in one embodiment,a full-sized laptop keyboard (about 11 inches long excluding its frame)to fold to 3.25 inches in length, including its housing.

Row III contains the wide “Enter” key 37 which spans two bottom hubs 6.FIGS. 14-16 illustrate a planar front view of the rotation of the keysof Row III shown in FIG. 13. To allow the keyboard assembly to fold to aminimum length and thickness, linkage 13 b, located between Rows III andIV, pivotally supports the front side of the “|\” key in Row IV at hub14 b, and has an angled extension 15 to pivotally support the back sideof the “Pg Dn” key in Row III at hub 16. Similarly, linkage 17, locatedbetween Row IV and Row V, pivotally supports the back side of the “|\”key at hub 18, and has an angled extension 19, to pivotally support thefront side of the “Home” key in Row V at hub 20. Linkage 13 shown inFIG. 13 includes a hub 14 a which couples the linkage 13 to an adjacentleg on the scissors linkage to the right of the “Enter” key. Theextension 15 of linkage 13 pivotally supports the front of the “Pg Dn”key at hub 16. This is also shown in FIG. 15. The hub 7 a is not coupledto the “Pg Dn” key but is coupled to the adjacent scissors linkage tothe right of the “Pg Dn” key.

FIGS. 14-16 show the wide “Enter” key 37 with normal width keys oneither side of the “Enter” key. No key in row 3 is attached at hub 14 awhich allows “Enter” key 37 to rotate unobstructed, but the “|\” key isattached to hub 14 b. FIG. 16 illustrates that when keyboard assembly 10is in its collapsed position, the vertical distance between hubs 6 and14 is sufficient to accommodate “Enter” key 37 without the key extendingbelow the bottom 38 of the series of linkages 4. FIG. 16 alsoillustrates that the wide keys and linkage extensions do not add to thehorizontal length of the folded keyboard assembly. The other wide keysof keyboard assembly 10 and their associated linkages and hubs aredesigned similarly, such that the folded depth of the keyboard is keptto a minimum.

In addition to accommodating keys of different widths, the linkagedesign of the invention allows keys on one row to be horizontallydisplaced with respect to keys on an adjacent row (e.g. staggered keycolumns), thereby conforming to standard keyboard layouts, such as forexample a “QWERTY” layout even though the rows are pivotally joined toeach other. For example, keys 3 in Row IV are pivotally supported on thefront side by hubs 7 of linkages 4 (FIGS. 6, 10, and 13). However,linkages 33 located between Row IV and Row V have angled extensions 21.This is illustrated in FIG. 13 and in a front view portion of Row Vshown in FIG. 17 in an expanded position and FIGS. 18-19 in a collapsedposition. As shown in FIGS. 13 and 17-19, there are two hubs 34 and 35on extensions 21, which lie on a horizontal axis when the keyboard isexpanded (FIGS. 13 and 17). In FIG. 13, linkage 33 pivotally supportsthe “{[” key of Row IV at hub 34. The same linkage 33 pivotally supportsthe “+=” key 3 of Row V at adjacent hub 35. In this manner, the keys inRow V are displaced horizontally with respect to the keys in Row IV.When fully collapsed, extensions 21 “nest” allowing the linkages to becompressed to their most compact position. This is illustrated in frontand rear views by FIGS. 18 and 19, respectively.

As shown in FIG. 13, hubs 34 lie along the same vertical axis as hubs 7which lie along the same vertical axis as rod 31. The X-shaped linkages4 and 33, respectively, and their respective extensions have centers ofintersections 5 which lie on a common vertical axis 36 for all rows,even though the keys of different rows are horizontally staggered andare of different widths. This arrangement allows all rows to expand andcollapse together.

While the keys in adjacent rows are horizontally staggered, the left andright terminations of the linkages in all rows lie in approximatelyvertical lines. Linkages supporting the left-most keys of each row(FIGS. 1 and 3) are aligned horizontally at their bottom hubs 6 andtheir top hubs 22. Similarly, linkages supporting the right-most columnof keys (FIGS. 1, 3, and 13) are aligned horizontally at their bottomhubs 6 and their top hubs 22. This allows a compact arrangement for ahousing composed of protective housing sides 1 and 2.

The left and right-most linkages of the embodiment of the keyboardassembly of the invention are pivotally joined to the housing sideportions 1 and 2, respectively, by bottom pivot pins 23 at bottom hubs 6and slidably joined to the housing side portions 1 and 2, respectively,by top pins 24, which slide in slots 25 of housing side portions 1 and2, respectively (see FIGS. 3, 4, and 5). Two sets of scissors orX-shaped linkages (without associated keys), located on the left- andright-most sides of keyboard assembly 10, allow the unit to be expandedso that housing side portions 1 and 2, respectively, are clear of keys3. In this manner, keyboard assembly 10 can be opened and closed in aone-step operation and does not need to be removed from its protectivehousing. In one embodiment of the invention, the surface of one ofhousing sides 1 and 2 may include a cursor control device such as asmall trackball, a touch-sensitive trackpad, a joystick, apressure-sensitive pointing device (e.g. IBM's TrackPoint III which isused on IBM's ThinkPad laptop computers), or other cursor control (e.g.pointing) devices. In addition, small buttons may be included on thesurface of the housing; these small buttons may perform the samefunctions as the buttons (or button) on a mouse which is often used witha computer. In another embodiment, the cursor control device isselectively positionable on either one of housing sides 1 and 2.

FIGS. 20-23 illustrate an additional feature of one aspect of anembodiment of a keyboard assembly of the invention. FIGS. 20, 22, and 23show front view portions of three keys in a row of keyboard assembly 10.FIG. 21 shows a vertical side view portion of keyboard assembly 10. Eachof FIGS. 20-23 illustrate an embodiment of a tilting device that raisesthe rear of keyboard assembly 10 for a comfortable angle similar to thatof desktop keyboards. FIG. 20 shows tilt fingers 26 extended whenkeyboard assembly 10 is in its fully expanded position and FIG. 23 showstilt fingers 26 retracted when keyboard assembly 10 is closed. In FIG.21, keyboard assembly 10 rests on a flat surface at the bottom tips offingers 26 and the front edge of left housing 1 and right housing 2.Thus, the rear of keyboard assembly 10 is elevated to provide acomfortable angle for typing as shown in FIGS. 20 and 21. Each finger 26is pivotally attached to the linkages 4 at hub 7 by a pin at this hub atthe back side of keyboard assembly 10. Flanged pin 27 passes through hub6. FIG. 22 shows the keyboard in a partially collapsed state. Askeyboard assembly 10 is collapsed (FIG. 22), pin 27 slides in slot 28,until collapse is completed (FIG. 23).

FIG. 24A shows a portion of one embodiment of a collapsible keyboard inan expanded position. Each row of keys 200 a-200 d has keys that areformed by a key top coupled to a key base. Rows 200 a and 200 d havekeys formed by a key top 201 coupled to a key base 202 a. Rows 200 b and200 c have keys formed by key top 201 coupled to a key base 202 b. Inone embodiment, the key tops are supported by the key bases throughconventional butterfly linkages (not shown) which allow the key tops tobe pressed down. An interconnected series of male struts 203 rotatablycoupled to female struts 204 in an X pattern connects adjacent rows. Forexample, key base 202 a in row 200 a is rotatably coupled to key base202 b in row 200 b by female strut 204 and a male strut in an adjacent Xpattern. Actuators 205 to facilitate key rotation are shown rotatablycoupled to male struts 203, to a female strut in an adjacent X pattern,and to key bases 202 b in rows 200 b and 200 c. Actuators 205 operate ina similar manner as arms 8, as described with reference to FIGS. 7-9. Inone embodiment, male struts 203, female struts 204, actuators 205, andkey bases 202 a and 202 b snap together for easier assembly. Althoughthe same key top 201 is shown for each key, it is appreciated that keytops of different sizes can be used. The male and female struts,actuator, and key bases are discussed in more detail below.

FIG. 24B shows the keyboard portion of FIG. 24A in a collapsed position.The keys in rows 200 a and 200 c have rotated counter-clockwise, whilethe keys in rows 200 b and 200 d have rotated clockwise. Male struts 203remain substantially parallel with one another, as do female struts 204,but the space between adjacent male struts 203 and between adjacentfemale struts 204 is decreased to give the collapsed position a thinprofile.

FIGS. 25A and 25B show two different views of a male strut or leg 250.The male strut 250 may be used as the male strut of FIGS. 24A and 24B.Main body 254 has protrusions 252 a, 252 b and 253 a, 253 b extendingorthogonally from both ends of main body 254. Protrusions 252 a and 253a are longer than protrusions 252 b and 253 b, respectively. Aprotrusion 251 extends orthogonally from approximately the middle of oneside of main body 254. In one embodiment, protrusions 251, 252 a, 252 b,253 a, 253 b are ridged to provide the snap-together feature mentionedabove. The flange or ridge at the end of these protrusions has adiameter which is slightly larger than the corresponding through hole inthe female strut which is designed to engage the protrusion. Once aprotrusion is snapped into its corresponding hole, the ridge retains themale and female struts. Extension stops 255 a and 255 b extend fromgrooves 256 a and 256 b, respectively, around protrusion 251. Extensionstops 255 a and 255 b limit keyboard expansion by stopping the rotationof a coupled female strut. In another embodiment, male strut 250 issymmetric about an axis perpendicular to the length of male strut 250,where the axis passes through the center of male strut 250.

FIGS. 26A and 26B show two different views of a female strut or leg 260that, in one embodiment, is coupled to male strut 250. The female strut260 may be used as the female strut of FIGS. 24A and 24B. Main body 264has end through holes 262 and 263 for mating with the protrusions ofmale struts in neighboring male-female X linkages when an interconnectedseries of X linkages is formed. A middle through hole 261 acceptsprotrusion 251 when male strut 250 and female strut 260 are coupledtogether to form an X linkage. Male strut 250 and female strut 260 arethus complementary. Extension stops 265 a and 265 b extending fromgrooves 266 a and 266 b, respectively, around middle through hole 261impinge upon extension stops 255 b and 255 a of male strut 250 askeyboard expansion occurs. In one embodiment, female strut 260 issymmetric about an axis perpendicular to the length of female strut 260,where the axis passes through the center of female strut 260.

FIGS. 27A and 27B show two different views of an actuator 270. Actuator270 has arms 274 a and 274 b. Arm 274 a has grooves 272 a and 272 b. Arm274 b has grooves 273 a and 273 b. Grooves 272 a and 273 a mate withprotrusions on a key base, and grooves 272 b and 273 b mate with one ofprotrusions 252 b and 253 b on male struts 250 in adjacent rows,depending on the orientation of male struts 250.

FIGS. 28A and 28B show top and bottom views, respectively, of a key base280. Flanges 284 a and 284 b extend out, above and below from oppositesides of base member 281. Protrusion 282 a extends out from one end offlange 284 a, and groove 283 a reaches partially through flange 284 a.Similarly, protrusion 282 b extends out from one end of flange 284 b,and groove 283 b reaches partially through flange 284 b. Protrusions 282a and 282 b mate with grooves 273 a and 272 a, respectively, of actuator270. In one embodiment, protrusions 282 a and 282 b are ridged toprovide a snap-together assembly with actuator 270. Grooves 283 a and283 b accept one of protrusions 252 b and 253 b of male strut 250,depending on the orientation of male strut 250. In one embodiment, keybase 280 is coupled to key top 201 to form the keys in rows 200 b and200 c. FIGS. 11 and 12 show one example of a way to couple a key top toa key base using a conventional butterfly linkage.

FIGS. 29A and 29B show top and bottom views, respectively, of a key base290. Key base 290 differs from key base 280 primarily in the position ofthe protrusion 292 a and protrusion 292 b; these different positionsallow for different pivot points for the different keys and allow acollapsible keyboard to have different size keys and still collapse.Flanges 294 a and 294 b extend out, above and below from opposite sidesof base member 291. Protrusion 292 a extends out from approximately themiddle of flange 294 a, and groove 293 a reaches partially throughflange 294 a. Similarly protrusion 292 b extends out from approximatelythe middle of flange 294 b, and groove 293 b reaches partially throughflange 294 b. Protrusions 292 a and 292 b mate with through holes in afemale strut or in some cases a groove in an actuator. Grooves 293 a and293 b accept one of protrusions 252 a and 253 a of male strut 250,depending on the orientation of male strut 250. It should be noted thateither of protrusions 252 a and 253 a of male strut 250 is long enoughto mate with both an end through hole 262, 263 of female strut 260 and agroove 293 a, 293 b. In one embodiment, key base 290 is coupled to keytop 201 to form the keys in rows 200 a and 200 d.

FIGS. 30A-30C show a side view of a portion of a row of keys in oneembodiment of a collapsible keyboard as the keyboard is collapsed. A keyclip 302 is disposed between a key top 301 and a key base 304. Althoughit is not shown for purposes of clarity, in one embodiment, a butterflylinkage couples key top 301 to key clip 302. Key clip 302 holds a flexcircuit 303 (e.g. a flexible bus of conductors) flat against key base304 by snapping onto key base 304 with flex circuit 303 in between. Ahook 305 at one end of key clip 302 guides flex circuit 303 down betweenadjacent keys, thereby allowing the keyboard to collapse more easily toa compact, closed position. The clip 302 relieves stress in the portionsof the flexible circuit 303 which bend by keeping one portion fixed(around the edge of the key base) and another portion loose (with a wideangle for bending).

FIGS. 31A and 31B show top and bottom views, respectively, of a key clip310. Tabs 312 a-312 d snap key clip 310 onto a key base (not shown) askey clip 310 is pressed against the key base. In one exemplaryembodiment, a flex circuit is laid on top of the key base before the keyclip is snapped into place onto the key base. Once key clip 310 issnapped onto the key base, a flex circuit (not shown) located betweenkey clip 310 and the key base is held flat against the key base. Guidearms 315 a and 315 b are curved downward to force the flex circuit downbetween adjacent keys. In one embodiment, each guide arm 315 a and 315 bguides separate layers of a flex circuit. Opening 313 allows contact tobe made with the flex circuit. Hooks 316 a and 316 b secure a butterflylinkage (not shown) that is coupled to and supports a key top.

FIG. 32 shows an example of a method of using a collapsible keyboard inaccordance with the teachings of the present invention. In step 401, afirst housing and a second housing are secured by a user's hands. Bothhousings are coupled to a collapsible support that supports a number ofkeys. In step 402, the housings are pulled apart linearly such that thekeys are exposed and the keyboard is expanded. In step 403, theexpansion of the keyboard is sensed (e.g. by a limit switch).

FIG. 33 shows another example of a method of using a collapsiblekeyboard in accordance with the teachings of the present invention. Instep 411, a first housing and a second housing are secured by a user'shands. Both housings are coupled to a collapsible support that supportsa number of keys. In step 412, the housings are pulled apart linearlysuch that the keys are exposed and the keyboard is expanded. In step413, the housings are pushed together such that substantially all of thekeys are covered and the keyboard is collapsed. In step 414, thehousings are latched together when the keyboard is collapsed.

FIG. 34 shows yet another example of a method of using a collapsiblekeyboard in accordance with the teachings of the present invention. Instep 421, a first housing and a second housing are secured, where bothhousings are coupled to a collapsible support that supports a number ofkeys. In step 422, the housings are pulled apart linearly such that thekeys are exposed and the keyboard is expanded. In step 423, power isautomatically provided to a keyboard circuit when the keyboard isexpanded.

Keyboard assemblies such as keyboard assembly 10, which is describedabove, normally require some associated electrical circuitry to detectthe actuation (e.g. pressing) of the various keys and the generation ofappropriate signals which indicate the identity of the actuated key.Typically, each key has an associated electrical switch which producesan electrical change of state (e.g. electrically open to electricallyclosed) when the associated key top is depressed.

In one embodiment of the keyboard assembly of the invention, each keybase 11 b includes electrical elements 39, 40, 41, and 42 and resistor503 and diode 504 as shown in FIG. 35. FIG. 35 illustrates an electricalconfiguration of four keys of keyboard assembly 10. Conductive paths(e.g. conductive strips) or electrodes 39 and 42 bend at right anglesover the face of key shoulders 43 on each key base 11 b and electricallycontact row linkages 4. On each key base 11 b, electrode 39 is coupledto one terminal of resistor 503, and electrode 40 is coupled to theother terminal of resistor 503. On each key base 11 b, electrode 40 isdisposed physically near, but electrically isolated from, electrode 41.Electrodes 40 and 41 are electrically coupled (e.g. “shorted”) when thekey top is pressed toward the key base; typically, when the key top ispressed, an electrode coupled to the key top shorts electrodes 40 and41, thereby closing the switch between electrodes 40 and 41. Electrode41 on each key base 11 b is coupled to one terminal of diode 504, andthe other terminal of diode 504 is coupled to electrode 42. Linkages 4are made of a conductive material such as, for example, steel, aluminum,or plastic which is conductive or which includes an electricallyconductive material. Each row of linkages 4 acts as a single wireelectrical bus 44. Each bus 44 is connected to a keyboard controller(not shown in FIG. 24) which could be located in one side of thekeyboard assembly housing. A cursor control device (such as a trackpad)and battery could be located in this same side of the housing or theother housing side. In another embodiment, a data transfer port iselectrically connected to each bus 44 through the keyboard controller orany other appropriate interface for communicating with a computersystem. The data transfer port may be a universal serial bus (USB) portor a “Firewire” port such as a port which substantially complies withIEEE Standard 1394.

In yet another embodiment, key bases 11 b and row spacing sleeves 32(see FIGS. 13 and 35) are made of a non-conductive material, such as,for example, plastic. Other materials (e.g. rod 31) in the keyboardassembly 10 which may serve as an electrical path from one row oflinkages 4 to another row of linkages 4 is also made from non-conductivematerials so that these rows remain electrically isolated. Hence, eachrow is electrically isolated from its adjacent row, although they sharea common framework of conductive linkages.

FIG. 36 shows a schematic diagram of one example of a typical keyencoder circuit 500 for a key. In the embodiment described herein, eachkey assembly, having a key top 11 a and a key base 11 b, contains a keyencoder circuit consisting of a key switch 502, a resistor 503, a diode504, and two terminals 501 and 505. In one embodiment, key switch 502(formed by electrodes 40, 41 and conductive face 45) is normally openand is closed when key top 11 a is pressed downward toward key base 11b. Diode 504 determines the polarity of the key circuit. Resistor 503determines the resistive load of the particular key 3 when switch 502 isclosed and diode 504 is biased with the current flow. Terminal 501 iscoupled to one bus 44 and terminal 502 is coupled to another bus 44.

FIG. 37 illustrates a row of 10 keys. Although FIG. 37 shows 10 keys inthe row, it is to be appreciated that the number of keys can be more orless than this amount. In this embodiment, each key assembly has oneterminal connected to bus 520 (which may be a row of scissors linkages)and the other terminal connected to bus 521 (which may be an adjacentrow of scissors linkages). Keys in the row are arranged in two polaritygroups with half of the keys, e.g., 510, 511, 512, 513, and 514, in onepolarity and the remaining keys, 515, 516, 517, 518, and 519, in theopposite polarity. Each key in a polarity group has a differentresistive load and the resistor values differ exponentially from key tokey. The keys are polarized by the diodes to allow the row of keys to bedivided into two sections to keep the ratio of the highest and lowestresistor values within a reasonable range, particularly when there are alarge number of keys coupled between adjacent busses 44.

FIG. 38 shows a schematic block diagram of a partial row of keys of akeyboard assembly in accordance with the invention. Key assemblies 580and 590 are coupled in parallel between conductive pathways or buses 575and 576. Key assembly 580 includes a switch 581 coupled to a transponder582, which receives power via wire 583. Key assembly 590 includes aswitch 591 coupled to a transponder 592, which receives power via wire593. Each transponder 582 and 592 is identified by a unique address. Inone embodiment, a keyboard controller sends addresses down the row ofkeys through bus 575. For each key that is pressed, thereby closing theassociated switch, the transponder coupled to that switch recognizes itsaddress and responds through bus 576. In one embodiment, transponders582 and 592 are ASIC (Application Specific Integrated Circuit)transponders. In one example, each transponder may transmit a unique,identifiable signal which is decoded by a keyboard interface which iscoupled to buses 575 and 576.

FIG. 39 shows a keyboard assembly consisting of an array of keys 640, akeyboard interface 600, and a microcontroller 650. In this example,array of keys 640 is 6 rows of 15 keys. Each key in each row isconnected in parallel on a two-wire bus with adjacent rows of keyssharing a common bus. For example, the top row of keys (keys 640 a, 640b . . . 640 o) are coupled in parallel on a two-wire bus formed byconductors 601 and 602. Conductor 601 may be a row of scissors linkages4 and conductor 602 may be an adjacent row of scissors linkages 4. Thus,each of conductors 601-607 may represent one of the busses 44 shown inFIG. 35. This arrangement has an advantage over traditionaltwo-dimensional key matrix arrays in that wire column buses are notrequired, thus decreasing the number of connections to keyboardinterface 600. This is particularly advantageous when the keyboard iscollapsible because wires in a collapsing structure may interfere withthe mechanics of collapsing, and the wires may also deteriorate overtime due to repeated expanding and collapsing of the keyboard.

FIG. 40 illustrates a keyboard interface 600 between array of keys 640and microcontroller 650. In this embodiment, analog multiplexers 608 and609 are used to enable one selected row of keys, in one polarity, at onetime. Row address inputs 621, 622, and 623 of multiplexer 608 determinewhich keyboard bus is connected to positive current sense signal 610.Row address inputs 624, 625, and 626 of multiplexer 609 determine whichkeyboard bus is connected to ground. Resistor 614 and 618 create avoltage divider to generate a reference voltage signal 619 foranalog-to-digital converter 611 and operational amplifier 616.Operational amplifier 616 outputs a voltage that is relative to theamount of current drawn at positive sense signal 610. Analog to digitalconverter 611 is used to digitize the amount of current drawn by thebus, by measuring the output voltage of operational amplifier 616, andmakes a resulting digital value available to microcontroller 650 via bus612. Signal 613 is provided by microcontroller 650 and is used to starta new analog-to-digital conversion when microcontroller 650 needs tomeasure the bus current.

In the embodiment of FIG. 40, in operation, microcontroller 650 scansthe keyboard assembly, one row at a time, by sequentially addressingeach row of keys using row address signals 621, 622, and 623 and 624,625, and 626. The row addresses for multiplexers 608 and 609 differ byone, in order to connect keyboard buses in adjacent pairs (e.g., 601 and602, 602 and 603, etc.). Keyboard buses 602, 603, 604, 605, and 606 areeach shared by two rows of keys, decreasing the number of connections tothe keyboard assembly. Each row is addressed twice, once in eachpolarity.

FIG. 41 shows an example of keyboard 640 with three rows of eight keyseach. Keyboard array 640 is coupled to keyboard interface 600 which iscoupled to microcontroller 650 which is coupled to host computer 653 oranother host device (e.g. a cellular phone, information appliance,personal digital assistant, etc.). On power-up initialization,microcontroller 650 sets all row addresses 621, 622, 623, 624, 625, and626 to a low state. Microcontroller 650 begins scanning the first row ofkeys by setting row address signals 621, 622, and 623 to a binary valueof one. This connects bus 601 to current source 610 and the input ofanalog-to-digital converter 611. Next, row address signals 624, 625, and626 are set to a binary value of two, connecting bus 602 to ground. Atthis point, if any keys 531, 532, 533, or 534 are pressed, theindividual key's diode will be forward biased, allowing current to flowthrough the key's resistor. At this same time, keys 535, 536, 537, and538 have no effect on the bus since their diodes are reverse biased.Since each of the keys, 531, 532, 533, and 534 have a different resistorvalue, microcontroller 650 can determine which keys are pressed byanalyzing the current flow as measured by the voltage drop acrossresistor 614. Microcontroller 650 then analyzes keys 535, 536, 537, and538 by setting row address signals 621, 622, and 623 to a binary valueof two and row address signals 624, 625, and 626 to a binary value ofone. This reverses the polarity by connecting bus 602 to current source610 and bus 601 to ground. In this state, keys 531, 532, 533, and 534have no effect and current flow through keys 535, 536, 537, and 538 canbe analyzed to determine which of the keys are pressed. This cyclecompletes scanning of the first row of keys and the remaining rows arescanned in a similar fashion. When microcontroller 650 finds a depressedkey, it uses a table look-up method to locate the scan code for the keyand sends the scan code to host computer 653 or other host device. Thisentire scanning process repeats indefinitely, causing the keyboard to becontinuously scanned.

Each key in a polarity group has a unique resistor value and, whenpressed, adds a specific resistive load to the bus. Any givencombination of pressed keys along a row generates a unique andidentifiable resistive load, allowing the keys pressed to be identifiedby the microcontroller 650. Therefore, the design allows accurate keyidentification even when multiple keys are pressed simultaneously alongthe same row.

FIG. 42A shows a key encoder 720 of another embodiment of a keyidentification system. Key encoder 720 has a timer 750 with twoterminals 751, 752. Timer 750 is coupled to a switch 753 and anelectrical identifier 754, which in one embodiment, is a resistor. Timer750 is a circuit with an output that is low when powered up and thenbecomes high after a predetermined time period, thereby reaching anactive state. Switch 753 is closed when a corresponding key (not shown)is pressed. When switch 753 is closed and the output of timer 750 ishigh, electrical identifier 754 adds an identifying load. In otherwords, even if switch 753 is closed, the identifying signal provided byelectrical identifier 754 does not become electrically visible until theoutput of timer 750 is high.

FIG. 42B shows a row of keys 761-765, each of which has a key encodersimilar to key encoder 720 but with different timers 750 a-750 e. Eachkey 761-765 is coupled to buses 701, 702. Timers 750 a-750 e are presetto unique time constants such that identifying loads are not added atthe same time. Although five keys are shown in a row, the presentinvention is not limited to any particular number of keys in a row.

FIG. 43 is a detailed illustration of a keyboard interface 700 used tocouple an array of keys to a microcontroller and may be used with thekey encoder shown in FIGS. 42A and 42B. Analog multiplexers 708, 709 areused to enable one selected row of keys at a time. Row address inputs721-723 of multiplexer 708 determine which keyboard bus 701-707 isconnected to a current sense signal 715. Row address inputs 724-726 ofmultiplexer 709 determine which keyboard bus is connected to ground.Resistors 717, 718 create a voltage divider to generate a referencevoltage signal 719 for an analog-to-digital (A/D) converter 711 and anoperational amplifier (op-amp) 716. Op-amp 716 outputs a voltage that isrelative to the amount of current drawn at current sense signal 715. A/Dconverter 711 digitizes the amount of current drawn by the bus connectedto current sense signal 715 by measuring and converting the outputvoltage of op-amp 716. The resulting digital value is sent to themicrocontroller by a bus 712. The microcontroller provides an A/D sampleclock signal 713 when the microcontroller needs to measure the buscurrent again.

FIG. 44 shows one implementation of keyboard interface 700 with an arrayof keys 740 coupled through buses 701-707 to keyboard interface 700which is coupled to a microcontroller 770 coupled to a host computer773. The keyboard system of FIG. 44 is shown using the key encoder 720of FIG. 42A for each of the keys. Array of keys 740 has six rows 741-746of fifteen keys. All keys in a row are connected in parallel on atwo-wire bus, with adjacent rows sharing a common bus. For example, rows741 and 742 share bus 702. By not requiring column buses, thearrangement of buses 701-707 decreases the number of connections tokeyboard interface 700 and prevents buses from crossing over oneanother. Microcontroller 770 scans array of keys 740, one row at a time,by sequentially addressing rows 741-746 using row address signals721-726. In one embodiment, the row addresses for multiplexers 708, 709differ by one such that adjacent buses are paired together (buses 701and 702 for row 741, buses 702 and 703 for row 742, etc.).

To scan row 741, microcontroller 770 sets row address signals 721-723 tothe binary equivalent of 1 and row address signals 724-726 to the binaryequivalent of 2. This connects bus 701 to current sense signal 715 andbus 702 to ground. Microcontroller 770 then determines which key(s)is/are being pressed according to the relative timing of signals, anexample of which is shown in FIG. 45 using the signals for keys 761-765.

Timer output signals 761 a-765 a for keys 761-765, respectively, go highsequentially at even time intervals. For example, timer output signal761 a goes high at t2 and timer output signal 762 a goes high at t4. Therelative bus current 710 drawn by bus 701 is shown with only keys 761,763 and 765 pressed. A/D converter 711 samples relative bus current 710when triggered by A/D sample clock signal 713 at odd time intervals.Starting with the sample taken at t3, microcontroller 770 compares eachsample with the previous sample to determine if a key has been pressed.In the example shown in FIG. 45, microcontroller 770 will determine thatkey 761 is pressed because a current increase occurred between thesamples taken at t1 and t3, and timer output signal 761 a for key 761 isthe only signal that goes high at t2 when its corresponding key ispressed. Microcontroller 770 will determine that key 762 is not pressedbecause a current increase did not occur between the samples taken at t3and t5, and timer output signal 762 a for key 762 goes high only at t4when key 762 is pressed. Microcontroller 770 checks each key in a row ina similar manner until all keys in a row have been checked. Although thetimer output signals for five keys are shown in FIG. 45, the presentinvention is not limited to any particular number of keys.

In another embodiment of the invention, microcontroller 770 verifies ascan by scanning a row a second time and comparing the results with thefirst scan. If the rescan does not match the first scan, the row isrescanned until two consecutive scans match. Once two consecutive scansmatch, the determination of pressed keys proceeds as described above. Ifmicrocontroller 770 finds any pressed keys, it uses a table look-upmethod to find the scan code(s) for the key(s) and sends the scancode(s) to a host computer 773 via bus 772. All of rows 741-746 arescanned similarly, row by row. The scanning process repeatsindefinitely, causing the keyboard to be scanned continuously.

FIG. 46 shows a linear matrix coupled to a row 800 of keys according toanother embodiment of a key identification system in accordance with theinvention. Row 800 is separated electrically into four sections 801a-804 a by the connections of the keys with section pathways 801-804.Section 801 a consists of keys 801 b-801 e, which are coupled to sectionpathway 801 (which may be considered to be an electrical row in anelectrical matrix). Section 802 a consists of keys 802 b-802 e, whichare coupled to section pathway 802 (which may be considered to beanother electrical row in the electrical matrix). Section 803 a consistsof keys 803 b-803 e, which are coupled to section pathway 803. Section804 a consists of keys 804 b-804 e, which are coupled to section pathway804. Thus, each section has its own electrical pathway and effectivelyeach section is an electrical matrix of key switches having at least oneelectrical row and several electrical columns. Each section may beregarded as an electrical section of an electrical matrix. Each key ineach section is also coupled to a key pathway, which is shared bycorresponding keys in each section. For example, keys 801 b, 802 b, 803b, 804 b are coupled to key pathway 805 (which may be considered acolumn) and keys 801 c, 802 c, 803 c, 804 c are coupled to key pathway806 (which may be considered another column). Thus, row 800 of keysappears electrically as if it were arranged in a 4×4 matrix, but thematrix is confined to row 800 which is a mechanical row of keys (e.g.row VI of FIG. 1), thereby allowing row 800 to be independent of andelectrically isolated from other rows. While FIG. 46 suggests that thekeys are mechanically and physically adjacent to each other along a row,it will be appreciated that the electrical sections along a row mayinclude, in any one electrical section, distantly spaced, non-contiguouskeys along the row (or another row in the case where the row [section]lines extend to the another row). This is accomplished by wiring up theswitches in each non-contiguous key to the desired row line. The linearmatrix defined by section pathways 801-804 and key pathways 805-808allows each key to be checked individually through the appropriatesection and key pathways. In one embodiment, the section pathway foreach section is provided by an electrode to which each key in thesection is coupled, and the key pathways for each section are providedby a group of electrodes, each one of which is coupled to a key in thesection. It should be noted that the sections can consist of any numberof keys and are not limited to having equal numbers of keys. In analternative embodiment, a row of keys could be separated into left andright electrical sections and each receives a wiring bus from itsrespective side.

In one exemplary embodiment of the invention, the section pathways andthe key pathways are, at least in part, provided by flexible conductorswhich may be flexible wires on a flexible plastic substrate. Theseflexible conductors may be positioned on the key bases and under the keytops as shown in FIGS. 30A through 30C. The flexible conductors allowthe keyboard to be expanded and collapsed as shown in FIGS. 30A through30C without requiring, on one row, as many conductors as is normallyrequired for a conventional keyboard electrical matrix (e.g. for amechanical row of 16 keys, a conventional keyboard electrical matrixrequires 17 conductors [16 column wires and 1 row wire], while thekeyboard electrical matrix requires only 8 conductors). Furthermore,flexible conductors electrically arranged in a matrix as in FIG. 46allow a row to be isolated electrically from other rows so that no“column” wires are required to interconnect between the rows. That is,all the wires for a row can run along the row and no wires (e.g. nocolumn wires) need to run between rows in the collapsible portion of thekeyboard assembly, thereby making mechanical expansion and contractioneasier to implement. This isolation between rows requires a separate setof column conductors for each row but this extra set is balanced by theimproved mechanical handling of the collapsible keyboard.

The flexible conductors may consist of one or more layers of flexiblematerial. For example, a single-layer conductor may have circuitsapplied to one face of a flexible material. It may have a pattern ofopen contacts under each key. When a key is pressed, an electricallyconductive puck attached to the key shorts the contacts, which completesa circuit.

In the preferred embodiment, a two-layer membrane is used. Thesemembranes each have circuits of silk-screened silver applied to theiropposing faces. The circuits are insulated by a coating such as lacquerexcept in the areas under each key, where they are separated by a raiseddeposit of material (for example, a pattern of non-conductive ink). Whena key is pressed, the two layers meet and their contacts join tocomplete a circuit.

A three-layer membrane has an insulating layer of non-conductivematerial between two layers, which have circuits of silk-screened silverapplied to their opposing faces. The insulating layer has a hole undereach key, such that when a key is pressed, the two outer layers meetthrough the hole and their contacts join to complete a circuit.

FIG. 47 is a block diagram of a keyboard array 150 with six rows 103-108of keys, where rows 103-108 are configured similarly to row 800 ofcoupled to a keyboard interface 100 which is coupled to amicrocontroller 101 which is coupled to a host computer 102 or otherprocessing system. In one embodiment, keyboard interface 100 allowsmicrocontroller 101 to access keyboard array 150 as if it were an 8×12(key X section) matrix by logically connecting common section and keysignals from rows 103-108. For example, rows 103-105 have common keysignals 109 a-109 c, and rows 103 and 106 have common section signals111 a and 111 b. In one embodiment, section signals 111 a-113 a and 111b-113 b are each associated with four sections in a row, and key signals109 a-109 c and 110 a-110 c are each associated with the four keys ineach of the four sections. For example, section signal 111 a isassociated with section S1-S4, and key signal 109 a is associated withkeys K1-K4. All key signals and section signals communicate withmicrocontroller 101 via keyboard interface 100 and interface signals 120and 130.

To begin scanning keyboard array 150, microcontroller 101 enters a modeof operation in which it activates all sections (S1-S12) throughinterface signal 130 to keyboard interface 100 and detects any responsethrough interface signal 120 from keyboard interface 100 to determine ifany keys are pressed. Microcontroller 101 remains in this mode andrepeats the process periodically until it detects a pressed key.

Once a pressed key is detected, microcontroller 101 enters another modeof operation in which it scans keyboard array 150, one section at atime, by activating individually each section (S1-S12) through interfacesignal 130 to keyboard interface 100 and detecting any response throughinterface signal 120 from keyboard interface 100. In an alternativeembodiment, one section in each of several rows may be activatedconcurrently to separately determine whether, in the appropriate sectionof each row, a key was pressed. Thus, several sections, each in anelectrically separate row, may be activated concurrently. For eachsection, a response signal will be supplied by one or more keysdepending on which keys in that section are pressed. Typically thesections are scanned in some order, such as a sequential order. Ifmicrocontroller 101 detects any response signal(s), it enters yetanother mode of operation in which it uses a table look-up method tofind the scan code(s) for the pressed key(s) and sends the scan code(s)to host computer 102. The entire scanning process repeats indefinitely,causing keyboard array 150 to be scanned continuously.

FIGS. 48A-48C show one embodiment of the key identification system shownin FIG. 46. Flexible lower layer 910 is disposed over a key base 900such that contact region 915 of lower layer 910 rests on key base 900.Flexible upper layer 920 is disposed over lower layer 910 such thatcontact region 925 of upper layer 920 is located directly above contactregion 915 of lower layer 910. In one embodiment, conductive traces911-914 are section pathways and conductive traces 921-924 are keypathways, where the section and key pathways are similar to thosedescribed with reference to FIG. 46. Contact regions 915 and 925 aredesigned to selectively bring two conductors (one from traces 921-924and one from traces 911-914) into electrical contact when the key top ispressed. In one embodiment, both ends of both lower layer 910 and upperlayer 920 (at the end of each row) are connectable to a cursor controldevice and to keyboard interface circuitry thereby allowing the cursorcontrol device to be positioned on either side of the keyboard; this isshown in FIG. 48E and is described further below. It should be notedthat FIGS. 48A and 48B show lower layer 910 and upper layer 920individually, respectively, to depict more clearly the features of lowerlayer 910 and upper layer 920.

In another embodiment of the invention, a keyboard assembly has multiplerows of keys where each row is coupled to a different conductive bus.Each row is also coupled to a different group of column electrodes, andeach key in the row is coupled to one row electrode. In other words,each row has its own row conductor, and each key in each row has its owncolumn conductor. FIG. 48D shows an example of such a system where amechanical row 944 of keys has a row conductor 940 and several columnconductors 941, and another mechanical row 945 of keys has anelectrically separate row conductor 942 and several column conductors943 (which may be electrically separate from column conductor 941).

FIG. 49 shows an example of a method for detecting key actuation inaccordance with the teachings of the present invention. In step 950, arow of keys is electrically separated into different sections (anexample of this is shown in FIG. 46). In step 951, the differentsections are scanned sequentially to detect a key actuation signal thatcorresponds to a pressed key. In step 952, a scan code corresponding tothe key actuation signal is sent to a host computer.

FIG. 50 shows another example of a method for detecting key actuation inaccordance with the teachings of the present invention. This method issimilar to the manner in which the keyboard array 150 of FIG. 47 isscanned. In step 960, a row of keys is electrically separated intodifferent sections (for example, as in FIG. 46). In step 961, thesections are scanned concurrently to detect a key actuation signal. Instep 962, if a key actuation signal is detected, then step 963 isperformed. If a key actuation signal is not detected, then the step 961is repeated. In step 963, the sections are scanned sequentially tofurther detect the key actuation signal. In step 964, a scan codecorresponding to the key actuation signal is sent to a host computer.

FIG. 51 shows yet another example of a method for detecting keyactuation in accordance with the teachings of the present invention. Instep 970, a row of keys is electrically isolated (for example, as inFIG. 46). In step 971, timers that are coupled to each key in the roware activated. In step 972, a first signal from the row of keys issampled at a first time. Then in step 973, a second signal from the rowof keys is sampled at a later time. In step 974, the sample of thesecond signal is compared with the sample of the first signal toidentify any pressed keys. In step 975, scan code(s) corresponding tothe pressed key(s) are located. In step 976, the scan code(s) is/aresent to a host computer. In another example, each key produces anidentifying signal when its timer is in an active state and the key ispressed. In another example, the timers reach an active state atdifferent times.

FIG. 52 shows still another example of a method for detecting keyactuation in accordance with the teachings of the present invention. Instep 980, a row of keys is electrically isolated. In step 981, timerscoupled to each key in the row are activated. In step 982, a firstsignal from the row of keys is sampled at a first time. In step 983, asecond signal from the row of keys is sampled at a later time. In step984, the second signal is resampled. In step 985, if the resample of thesecond signal substantially matches the first sample of the secondsignal, then step 986 is performed. If the resample and the first sampledo not substantially match, then step 984 is performed again. In step986, the resample of the second signal is compared with the sample ofthe first signal to identify any pressed keys.

In one embodiment of the invention, the surface of one of housing sides1 and 2 may include a cursor control device such as a small trackball, atouch-sensitive trackpad, a joystick, a pressure-sensitive pointingdevice (e.g. IBM's TrackPoint III which is used on IBM's ThinkPad laptopcomputers), or other cursor control (e.g. pointing) devices. Inaddition, small buttons may be included on the surface of the housing;these small buttons may perform the same functions as the buttons (orbutton) on a mouse which is often used with a computer. In anotherembodiment, the cursor control device is selectively positionable oneither one of housing sides 1 and 2.

FIG. 48B shows one example of an embodiment of the invention in which acursor control device, such as a track pad, is selectively positionableon either side of a keyboard, such as a collapsible keyboard assemblyaccording to the present invention. In this way, a user of such akeyboard may position the cursor control device on either the left sideor the right side of the collapsible keyboard depending on the user'spreference. In another embodiment, a cursor control device can be placedbetween the keys. For example, a pointing stick, such as IBM'sTrackPoint (found on IBM's ThinkPad laptop computers) can be placedbetween the G, H, & B keys. The flexible conductors associated withadjacent rows of keys can conduct the electrical signals from thepointing stick to the keyboard controller. In addition, small buttonswitches may be included on the surface of the first row of scissorslinkages; these small switches may perform the same functions as theswitches (or switch) on a mouse which is often used with a computer.

In the example shown in FIG. 48E, a keyboard is assumed to communicatewith a host computer or other host processing systems such as a personaldigital assistant. However, the keyboard may include a complete computersystem as shown in FIG. 53 and also provide the capability ofselectively positioning the cursor control device on either side of thekeyboard. The keyboard 1001 shown in FIG. 48E includes a key assembly1004 having end plates 1005 and 1006. Two rows of keys are shown, but itwill be understood that fewer or more rows of keys may exist. Each rowof keys includes section lines and key lines, such as section lines 1007or 1009 and key lines 1008 or 1010. The keyboard 1001 may be implementedas a collapsible keyboard by using scissors linkages or by allowing thekeyboard to fold (e.g. fold in halves or thirds at hinged joints whichseparate foldable sections of the keyboard). It will be understood thatsection lines 1007 are similar to section lines 801-804 of FIG. 46 andthat key lines are similar to the key lines 805-808 of FIG. 46. Each ofthese groups of lines includes a connector which may be mounted to theend plates and which allows the lines to couple to module 1003 whichincludes the cursor control device 1115. These connectors, shown asconnectors 1111 a, 1111 b, 1111 c, and 1111 d are located on either sideof the assembly of the keys 1004, thereby allowing the module 1003 to becoupled to either side of the assembly of keys. As shown in FIG. 48E,the module 1003 is coupled to the left side of the assembly while themodule 1002 is coupled to the right side. This may be reversed bydisconnecting module 1002 from the right side and disconnecting themodule 1003 from the connectors on the left side and coupling it throughmodule 1003's connectors 1111 e, 1111 f, 1111 g, and 1111 h to thecorresponding connectors 1111 a, 1111 b, 1111 c, and 1111 d on the rightside of the key assembly. The module 1003 includes a cursor controldevice 1115 which is coupled to a keyboard interface and I/O interface1116 which also provides a cursor control device controller. Thiscomponent 1116 provides conventional cursor control interface as well asI/O (input/output) interface functionality and keyboard interfacefunctionality. For example, component 1116 may provide the functionalityof the keyboard interface 100 and the microcontroller 101 shown in FIG.47 in addition to providing the functionality of controlling the cursorcontrol device. In addition, component 1116 provides the I/O interfaceto a host computer through the connection 1117. In an alternativeembodiment, the connection may be a port located in the middle of therear of the collapsible keyboard; this port is mechanically like anotherkey except that space around the port may exist because there are noadjoining keys next to the port and thus, a keyboard may still collapsewithout impinging on the port. Component 1116 is coupled to theconnection ports on the left side of module 1003 by bus 1114 b, and itis coupled to the connection ports on the right side of the module 1003by the bus 1114 a. It will be appreciated that module 1002 may be emptyor may contain electronic components which are appropriate for thedevice. For example, the module 1002 may include a small liquid crystaldisplay or a storage device or both, and these components and module1002 may be coupled through a flexible conductor bus to module 1003. Inone embodiment of the invention, a complete personal digital assistantmay be assembled into the collapsible keyboard by using the space withinthe modules 1003 and 1002. An example of such a system will now bedescribed in conjunction with FIG. 53.

FIG. 53 shows an example of a collapsible keyboard system 1050 with acollapsible keyboard assembly 1051 and a processor module 1052. Theprocessor module may be housed in the housing 1 or the housing 2 shownin FIG. 1 or may be housed in both housings with flexible conductorsproviding signals between the two housings as necessary. Module 1052includes a keyboard controller 1053, memory 1054, a system bus 1055, amicroprocessor 1056, and an input/output controller 1057. The modulealso includes two input/output ports 1058 and 1059. The keyboardcontroller 1053, the memory 1054, the microprocessor 1056, and the I/Ocontroller 1057 are interconnected by the system bus 1055. The keyboardcontroller 1053 may be a controller which provides the functionality ofthe keyboard interface 100 and the microcontroller 101 of FIG. 47 or itmay be other types of keyboard interfaces and/or microcontrollers whichcan provide scan codes to the system bus 1055 for use by themicroprocessor 1056 and/or storage into memory 1054. The memory 1054 maybe DRAM or flash memory or other types of storage devices. Furthermoreit may include mass storage such as a magnetic hard disk or other typesof mass storage to the extent it is possible to include such memory in asmall space. The microprocessor 1056 may be any conventionalmicroprocessor or microcontroller although it is preferable that it is ageneral purpose microprocessor which is controlled under control ofcomputer program instructions which are stored in memory 1054.Alternatively, the microprocessor 1056 may be a microcontroller which,on a single semiconductor substrate, includes the memory which storesthe computer program which is executed by the microcontroller. The I/Ocontroller 1057 may be a conventional input/output controller which canperform direct memory access to the memory 1054 and which also cancommunicate data to and from the microprocessor 1056. The I/O controller1057 provides input and output control for the two ports 1058 and 1059.In one example of the present invention, the input/output port 1058 maybe a universal serial bus (USB) port or an infrared port or a serialport (such as an RS-232 port) or a conventional parallel port. The otherinput/output port may be a Firewire port, which may be considered to bea port which substantially complies with the IEEE standard known as1394. This Firewire port may provide output to a display device such asa miniature head-mounted display which can project to a viewer's eye animage of a display. Alternatively, this port 1059 may be coupled to astandard computer monitor rather than a miniature head-mounted display.It will be appreciated that in one embodiment, no display is includedinto the collapsible keyboard system 1050, but rather, data for thedisplay is separately provided through the port 1059 as describedherein. Another example of a port may be a port which complies with thePCMCIA standard, such as the conventional PC Card or PC Card bus portsfound on modem laptop computers.

In one example of the present invention, the input/output port may be auniversal serial bus (USB) port or a serial port (such as an RS-232port) or a “PS/2” port or an infrared port or a radio frequency port ora parallel port or a Firewire port, which may be considered to be a portwhich substantially complies with the IEEE standard known as 1394 orseveral ports providing a combination of these ports.

In another example of the present invention, a “docking station” may beprovided to accommodate various devices such as Palm Computing's“PalmPilot.” In this example, the docking station consists of amechanical/electrical connector which allows the PalmPilot to mount tothe rear of the keyboard and communicate with the keyboard through thePalmPilot's serial interface. In this manner, the user can comfortablyenter data with the keyboard while viewing the PalmPilot's display. Thekeyboard may also include an additional port for a wired or wirelessmodem. With this configuration, the keyboard and PalmPilot could be usedfor sending and receiving e-mail or various Internet applications.Wireless phones and other information appliances may be docked in asimilar manner. Additional flexible conductors associated with the lastrows of keys can conduct the electrical signals from the docked deviceto the keyboard controller.

An alternative embodiment of a keyboard assembly of the presentinvention uses alphanumeric keys which use only two different keyassemblies for a collapsible keyboard. In one embodiment of the presentinvention, the scissors linkage structure has pivot points which aredesigned to reach a pitch of approximately 19 millimeters from eachother when the structure is fully expanded. The key switch assembliesattach to these pivot points, and common pivot points are shared betweenadjacent rows on the collapsible keyboard. However, standard keyboardlayouts typically require that the keys in one row be offset from keysin the next row by a fixed dimension. In one example the offset betweenthese rows is approximately one-quarter of a key width.

It is possible to satisfy this offset between the rows while using onlytwo key assemblies which are designated as key assembly A and keyassembly B. The relative center key position difference between key Aand key B is one-quarter of a key width. Therefore, if key A assemblieswere placed in one row and key B assemblies were placed in an adjacentrow, the two rows would be offset each other by one-quarter of a keywidth. Since in one design the collapsing keyboard requires some rows tofold left and others to fold right, this is taken into account whenpositioning the key center of key A and key B relative to the pivotpoint of the scissors linkage structure. The result of this is that thekey A center is ⅜ of a key width from the pivot point and key B is ⅛ ofa key width from a pivot point. The combination of ¼ key offset and ⅛ to⅜ pivot offsets creates additional combinations of offsets. Further,increments of ¼ key offsets can be combined to give ½ key offsets invarious folding directions.

The foregoing description provides examples of different embodiments ofthe invention. Other implementations will be appreciated by thoseskilled in the art. For example, rather than using scissors linkages, asupport element for the keys may be a telescoping set of elements whichslide along each other to expand and collapse. Each key may be pivotallycoupled to two such elements and rotate upon expanding or collapsing.The keys in one embodiment may use thin membrane switches withoutbutterfly linkages or springs, and thus the key top and key base may beused to cause two conductive to come into electrical contact. Further,these membrane switches may fold rather than pivot. A membrane switchmay be coupled to a telescoping or scissors linkage support member attwo points and may fold as a cloth seat of a director's chair folds whenthis chair is collapsed. A flexible conductor assembly may be disposedon a surface of the membrane switch and may fold with the membraneswitch. In certain embodiments, a keyboard assembly of the invention mayinclude certain ergonomic features, such as a split keyboard or apalmrest which may be attached and detached from the keyboard assembly.

In other embodiments of the invention, the relative functions of therows and columns may be reversed. For example, the columns, rather thanthe rows, may fold/collapse to achieve a keyboard which can decrease indepth but not width. This may be implemented by providing columns ofscissors linkages rather than rows of scissors linkages. In a relatedway, the columns of keys may be electrically isolated in a similarfashion as the rows are electrically isolated (as in, for example, FIGS.46 and 48D), and each column may include several electrical sections ofan electrical matrix which is separate and distinct from anotherelectrical matrix formed in another column. Other modifications andimplementations will be appreciated from this disclosure.

In the preceding detailed description, the invention is described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention as setforth in the claims. The specification and drawings are, accordingly, tobe regarded in an illustrative rather than a restrictive sense.

1. A keyboard assembly for entering data, said keyboard assemblycomprising: a first conductive member; a first row of keys each having afirst electrical element which is electrically coupled to said firstconductive member; and a second row of keys each having a secondelectrical element which is electrically coupled to said firstconductive member.
 2. A keyboard assembly as in claim 1 wherein saidfirst row is adjacent to said second row.
 3. A keyboard assembly as inclaim 1 wherein said first row of keys is electrically isolated fromsaid second row of keys.
 4. A keyboard assembly as in claim 1 furthercomprising a second conductive member which is electrically coupled tosaid second row of keys.
 5. A keyboard assembly as in claim 4 whereinsaid second row of keys is coupled in parallel between said firstconductive member and said second conductive member.
 6. A keyboardassembly as in claim 1 wherein said first electrical element is a firstswitch and said second electrical element is a second switch.
 7. Akeyboard assembly as in claim 6 wherein each key of said first row ofkeys comprises an identifying electrical element which identifies saideach key determined by a state of said switch of said each key.
 8. Akeyboard assembly as in claim 6 wherein said first row of keys and saidsecond row of keys are electrically sensed separately and sequentially.9. A keyboard assembly as in claim 8 wherein said first row is adjacentto said second row.
 10. A keyboard assembly for entering data, saidkeyboard assembly comprising: a first conductive member; a secondconductive member; and a first plurality of keys electrically coupled tosaid first conductive member and to said second conductive member, eachof said keys comprising an electrical identifier and a switch whichprovides a signal through at least one of said first conductive memberand said second conductive member which identifies said each of saidkeys.
 11. A keyboard assembly as in claim 10 wherein said firstplurality of keys are electrically coupled in parallel between saidfirst conductive member which is flexible and said second conductivemember which is flexible.
 12. A keyboard assembly as in claim 10 whereinsaid each of said keys further comprises a biasing element coupled tosaid electrical identifier to electrically bias said electricalidentifier.
 13. A keyboard assembly as in claim 12 wherein said biasingelement comprises a diode.
 14. A keyboard assembly as in claim 10wherein said first conductive member and said second conductive memberare mechanically coupled to said first plurality of keys to support saidfirst plurality of keys.
 15. A keyboard assembly as in claim 14 furthercomprising: a third conductive member; a fourth conductive member; and asecond plurality of keys electrically coupled to said third and saidfourth conductive members, each of said keys of said second plurality ofkeys comprising another electrical identifier and another switch whichprovide another signal through at least one of said third and saidfourth conductive members.
 16. A keyboard assembly as in claim 15wherein said first plurality of keys form a first row of keys and saidsecond plurality of keys form a second row of keys which is adjacent tosaid first row of keys.
 17. A keyboard assembly as in claim 14 furthercomprising a housing which is coupled to said first conductive memberand said second conductive member, and wherein said housing is part of aportable computer.
 18. A keyboard assembly as in claim 17 wherein saidkeyboard assembly is not collapsible.
 19. A keyboard assembly as inclaim 14 wherein said electrical identifier comprises a resistor.
 20. Akeyboard assembly as in claim 14 further comprising: a third conductivemember; and a second plurality of keys electrically coupled to saidthird conductive member and said second conductive member, each of saidkeys of said second plurality of keys comprising another electricalidentifier and another switch which provide another signal through atleast one of said second conductive member and said third conductivemember which identifies said each key of said second plurality of keys.21. A keyboard assembly as in claim 20 wherein said first plurality ofkeys form a first row of keys and said second plurality of keys form asecond row of keys, and wherein said first row of keys and said secondrow of keys are electrically sensed separately and sequentially.
 22. Akeyboard assembly for entering data, said keyboard assembly comprising:a first row of keys disposed mechanically along at least a first supportmember; a first section of an electrical matrix coupled to a firstportion of said first row of keys; and a second section of saidelectrical matrix coupled to a second portion of said first row of keys.23. A keyboard assembly as in claim 22 wherein said first section of anelectrical matrix comprises a first electrode coupled to each key ofsaid first portion of said first row of keys and a first plurality ofelectrodes, each electrode of said first plurality of electrodes coupledto one key of said first portion of said first row of keys, and furtherwherein said second section of an electrical matrix comprises a secondelectrode coupled to each key of said second portion of said first rowof keys and a second plurality of electrodes, each electrode of saidsecond plurality of electrodes coupled to one key of said second portionof said first row of keys.
 24. A keyboard assembly as in claim 22further comprising: a second row of keys disposed mechanically along atleast a second support member, said second row of keys beingelectrically isolated from said first row of keys; a third section ofanother electrical matrix coupled to a first portion of said second rowof keys; and matrix comprises at least two row conductors and at leasttwo column a fourth section of said another electrical matrix coupled toa second portion of said second row of keys.
 25. A keyboard assembly asin claim 22 further comprising a signal detector coupled to said firstsection of an electrical matrix and said second section of saidelectrical matrix, said signal detector being configured to scansequentially said first section and said second section of saidelectrical matrix.
 26. A keyboard assembly as in claim 22 wherein saidfirst section and said second section of said electrical matrix areprovided by a first conductive layer and a second conductive layer andwherein said electrical matrix comprises at least two row conductors andat least two column conductors.
 27. A keyboard assembly as in claim 26wherein each key of said first row of keys comprises a key base and akey top, said first and second conductive layers having portionsdisposed between said key base and said key top, said each key beingconfigured to hold said first and second conductive layers against anedge of said key base.
 28. A keyboard assembly as in claim 26 whereineach of said first and second conductive layers has a first end and asecond end, each of said first and second ends being couplable to acursor control device.
 29. A keyboard assembly as in claim 26 whereinsaid first and second conductive layers are flexible and wherein saidfirst plurality of electrodes and said second plurality of electrodesare the same.
 30. A keyboard assembly for entering data, said keyboardassembly comprising: a conductive member; and a row of keys electricallycoupled to said conductive member, each key of said row of keyscomprising a timer and a switch, said timer controlling a signalprovided by said switch.
 31. A keyboard assembly for entering data, saidkeyboard assembly comprising: a conductive pathway; and a row of keyscoupled to said conductive pathway, each key of said row of keyscomprising a switch coupled to an active electrical identifier, saidactive electrical identifier of said each key providing a uniqueidentifying signal.